PWM-Less Utility Frequency Output Capacitive Wireless Power Transfer System

This paper presents a capacitive wireless power transfer (CPT) system designed to provide utility frequency output, specifically targeting onboard chargers (OBCs) for electric vehicles (EVs) in automated parking systems. The system functions by directly injecting high frequency into a fully rectified sinusoidal waveform, thus removing the need for DC link capacitors. On the secondary side, the waveform is converted back into a fullwave rectified sinusoid using a diode rectifier and filter. The unfolder on the secondary side provides the utility frequency output without pulse width modulation (PWM). This topology reduces switching losses and supports system miniaturization. Experimental results from a prototype show AC voltage output at a utility frequency of 50 Hz. The analysis reveals a total harmonic distortion (THD) of 4.10% for the input current and 5.43% for the output current.